题目

If anyone happens to drop in while I'm out, ____ him or her leave a message. A.have                           B. get                         C. ask                         D. tell 答案：A①观察DNA、RNA在细胞中的分布 ②观察根尖细胞的有丝分裂③探究酵母菌的呼吸方式 ④叶绿体色素的提取和分离A. ②③ B. ③④ C. ①② D. ①④